Photographic reproduction in three dimensions



Sept. 3, 1968 K. 1.. AGNEW 3,399,993

PHOTOGRAPHIC REPRODUCTION IN THREE DIMENSIONS Filed Jan. 8, 1965 4Sheets-Sheet l Fig.2

Sept. 3, 1968 K. L. AGQNEW 93 PHOTOGRAPHIC REPRODUCTION IN THREEDIMENSIONS Filed Jan. 8, 1965 4 Sheets-Sheet 2 5e 5f 3f If- 1e.

P 1968 K. L. AGNEW 3,399,993

PHOTOGRAPHIC REPRODUCTION IN THREE DIMENSIONS Filed Jan. 8, 1965 4Sheets-Sheet s Fij- 7 P 3, 1963 K. L. AGNEW 3,399,993

PHOTOGRAPHIC REPRODUCTION IN THREE DIMENSIONS Filed Jan. 8, 1965 4Sheets-Sheet 4 United States Patent PHOTOGRAPHIC REPRODUCTION 'IN THREE"DIMENSIONS Kenneth Leslie Agnew, Falconbridge, Ontario, CanadaContinuation-in-part-of application Ser. No. 108,010, May 5, 1961. Tapplicationjan. 8,,1965, Ser.

4 Claims. (Cl. 96-27) ABSTRACT OF THE DISCLOSURE This is acontinuation-in-part of application Ser. No. 108,010 for PhotographicReproduction in Three Dimensions, filed May 5, 1961, now abandoned, andrelates to a method of recording the shape of three-dimensional objectsand reproducing them photographically, in three dimensions, inside thespace occupied by a transparent differentially-photosensitive material.

Lines are projected onto the object whose shape is to be recorded, andthe resulting contour lines are recorded in two or more views atdifferent angular relationship to each other. The resulting views ofeach contour line are reprojected, one multiple-viewed contour line at atime, and with the same angular relationship, into the space occupied bya transparent differentially-photosensitive material, so that the lineof intersection of the projected views recreates the contour line withinthe space occupied by this material. The intensification of illuminationat the line of intersection of the sheets of reprojected energy, in atransparent difierentially-photosensitive material, will then provide arecord, within the space occupied by the material, of each contour line,similar to the shape of the contour line produced by the original sheetof light as it impinged on the original shape. The sum of the contourlines reproduced outlines the threedimensional image.

The present invention will be more fully understood from the followingdescription:

FIGURE 1 is a diagrammatic plan of an arrangement used to obtain arecord of the contour lines.

FIGURE 2 is a view of six lines which were projected onto the shape tobe reproduced.

FIGURE 3 is a composite record of the six resulting contour lines,together with a partial outline of the shape to be reproduced, as vieweddirectly by the camera.

FIGURE 4 is a composite record of the six resulting contour lines,together with a' partial outline of the shape to be reproduced, asviewed in a mirror at a different angle to that in FIGURE 3, reversed tocompensate for the reversal of the mirror image, and enlarged to thesame scale as FIGURE 3.

FIGURE 5 is a diagrammatic plan of an arrangement used to reproject theimages of the contour lines onto the original shape, for illustrativepurposes.

FIGURE 6 is a composite record of the reprojected views shown in FIGURES3 and 4, when properly intersecting on the shape, together with apartial outline of the a shape.

ice

FIGURE 7 is -a composite record, similar to that in FIGURE 6, but withthe shape slightly out of the position where the reprojected sheets ofenergy intersect.

FIGURE 8 is a portion of a section of a transparentdifferential]y-photosensitive material with rays of reprojected energydrawn to intersect at points on the reproduced contour line.

FIGURE 9 is a view of the shape to be reproduced, in outline, with twocontour lines superimposed.

FIGURE 10 is another view of the shape to be reproduced, in outline,with two contour lines superimposed, taken from a different angle thanthe View shown in FIGURE 9.

FIGURE 11 is a third view of the shape to be reproduced, in outline,with two contour lines superimposed, taken from a different angle thanthe views shown in FIG- URES 9 and 10.

FIGURE 12 is a portion of a section of a transparentdiiferentially-photosensitive material, at a different level than FIGURE8, with rays of reprojected energy drawn to intersect at points on thereproduced uontour lines, and demonstrating why adjacent lines must bereprojected sequentially; auxiliary series of lines illustrate methodsof adjustment of angle of entering rays of energy.

Referring first to FIGURE 1, 11 is a projector throwing an image of aline (which is a primary line) along a path 12 onto the shape to bereproduced 7, in this case a tilted football. The image of the line onthe football is recorded by path 13 direct to the camera 10, and also bypath 14, at Angle A to path 13, to the mirror 9, supported by stand 8,and thence by path 15 to the camera 10 (these recorded lines beingsecondary lines). Instead of the mirror, of course, another camera maybe set up on an extension of path 14, to record directly. Also, morethan two cameras or one mirror may be used, with the path of eachrecording image at an angle to all the others, to give more than twoviews. and thus intensify the contrast at the line of intersection whenreprojected as described below; in some cases only one record, or camerais required, as is also mentioned below 1', 2, 3, 4, 5 and 6, FIGURE 2,are lines which may be projected and viewed successively, orsimultaneously if a tracing device with coupled reprojector is used,shown as a composite, and FIGURES 3 and 4 are, respectively, compositesof the direct view and the view via the mirror of the projected andrecorded lines 1, 2, 3, 4, 5 and 6, on the football. FIGURE 4 is shownreversed to correct for the mirror reversal, and is so reprojected. Inthis illustration, the few lines are shown widely spaced, but inpractical application many would normally closely adjoin or overlap eachother.

FIGURES 5, 6 and 7 demonstrate the reprojection of the contour lines,shown in FIGURES 3 and 4. In this case, for example, contour line 1}from FIGURE 3 was projected by projector 16, FIGURE 5, along the samepath 13, and onto the same football 7, as was shown in FIGURE 1.Simultaneously contour line 1E, FIGURE 4 was projected by projector 15,FIGURE 5, along the same path 14, and onto the same football 7, as areshown in FIGURE 1. When properly intersecting they coincide as one line1g, FIGURE 6, similar to that originally recorded as in FIGURE 1. FIGURE6 is a composite reproduction made in similar fashion from thesuccessive reprojections of the pairs of lines shown in FIGURES 3 and 4,to produce 1g, 2g, 3g, 4g, 5g, and 6g where they intersect as shown inFIGURE 6.

It is obvious, from the above, that one of each set of reprojectedcontour lines may be the originally projected line, used withoutpreliminary two-dimensional replication, as, if projected into thetransparent differentiallyphotosensitive material at the same angle asthe original line was projected for primary record, the sheet ofprojection would have the same cross-sectional shape as if itwasphotographed by a jector 11, FIGURE 1, and then the photographed linereprojected by a projector "at the same position as the camera 10,vFIGURE 5, assuming this camera has the same relative position to lines.13 and/or 14 as projector 11, FIGURE 1. Indeed, in the usual case ofthe original projections being straight lines, no difficulties regardingenlargement or reduction of size of these lines arises, to co-ordinatewith the lines emitted by, say, projectors 15 and/or 16, FIGURE 5. Thisis clearly shown by referenoe..to the reproduction of straight lines inFIGURE 6, by reprojection of lines lf to FIGURE 3, and .1.e to 52,FIGURE 4, and which was viewed at the same angle as the originalstraight contour lines 1 to 5, FIGURE 2, were projected.

Projection of lines is described, but these lines may be considered tobe shortened to the length of a dot, although this would often be aninefiicient method. Similarly a series of dots or dashes can beconsidered a line, even though it is discontinuous. The size of linesmay be varied-in reproduction, providing similarity in shape andrelative position to each other are maintained.

FIGURES 8 to 12 clarify my method further. Consider the transparentdifferential]y-photosensitive material 17 as a plastic, which, at C.above the ambient temperature, becomes opaque, and that all raysentering the plastic are of sufficient energy, and the absorptioncoefiicient of the plastic is such that for the first inch ofpenetration, during the unit of time of exposure, the temperature in thepath of each ray is raised about 5 C., and 4 /2 C. for the second inch,et cetera (actually '1=I e* Consider that FIGURE 9 is a reflectivesurface, except for lines If and 3 and is pasted to face CE as shown inFIGURES 8 and 12, so that section CC appearsat the level of FIGURE 8 andsection EE at the level of FIG- URE 12; and similarly FIGURE 10 ispasted to face PG, and FIGURE 11 to face DB. Now if lines 3 3h, and 3eare blanked out, and the three faces are illuminated normally byparallel rays from the three directions shown (preferably with coherentlight to decrease side effects .due to diffraction on passage throughthe slits 1 111, and 1e), thethree rays lfC, lhF and leD will passthrough the corresponding slits 1f, lit and 1e at the correspondingpoints 33, 34 and 35, at the level of the section shown. in FIGURE 8,each one heating the plastic by about 4 /2 as they near the pointofiintersection. However, at their point of intersection, 39, theireffect is cumulative, causing an elevation of temperature of about 13 /2at this point only, and therefore creates an opaque spot at 39 only,under the given conditions.

Similarly at the section shown as FIGURE 12, parallel light passingnormally through slits 1), 1h and 1e at corresponding points 36, 37 and38, will produce an opaque spot at the point of intersection 40, and sofor all the lines where the rays from 1 1h and 1e intersect, within thetransparent diiferentially-photosensitive material 17.

Now, if the first line of intersection is allowed to cool, slits 1 111and 1e are blanked out, and slits 3], 311 and 3e are uncovered, andrays, as above, projected through them simultaneously, a second opaqueline, including points 41, FIGURE 8, by rays 3fC, 3hF and 32D passingthrough the respective points 27, 28 and 29, and 42, FIGURE 12, by rays3fE, 3hG and 3eB passing through the respective points 30, 31 and 32,will be produced within thetransparent differentially-photosensitivematerial 17.

By originally projecting a sufficient number of lines, as partiallyindicated in FIGURES 1 and 2 of my application, and obtainingcorresponding multi-angular views of each line, a curved surface may bebuilt-up within the transparent differentially-p11otosensitive material,by the adjacent lines of intersection. The reprojections may be of linesas a whole, or pencils of energy drawn along the lines to sweep out thesheets of energy.

camera superimposed on pro-.

,,,In FIGURE 12 I have circled points 43,44 and 4519 illustrate whyadjacent lines, or areas, may not be projected simultaneously, as thesepoints would not lie on the desired surface of reproduction, and wouldobscure it. Of course, it may be possible, in some cases, to reprojectwidely.s.eparated-sets,of lines simultaneously, if the separation issuch thatthe'intersecting sheets do not interfere as describedabove,=and the degree of necessaryseparation depends on the magnitude"of .the-a-ngle='b etween component sheets of "projection of a set.Ineffect, this means that separated areas being reproduced ma be formedby sequential build-up ofeach area, simultaneously in the differentareas;if points of intersection from the different areas do, notinterfere with the desired surface.

In the illustration above, FIGURE 1, lines are shown projected on to theshape from one direction only, and viewed and then reprojected, FIGURES5 and 7, from two directions. Obviously, for a complete solid shape, theoriginal lines must be projected from more than one direction, spacedaround the' shape, and each image of a line on the object recorded by atleast two views ata suitable angular relationship to each other,(bearing in mind that one of the views may be the originally projectedlines and need not be recorded in conjunction with the object), andthese single-line views reprojected simul taneously into the transparentdifferentially-photosensitive material at the same angle as recorded,the multiplicity of successive resulting contour lines at intersectionbuilding up the three-dimensional image. To do this it will usually alsobe. necessary to have cameras and projectors in planes at angles to eachother (ormirrors at suitable angles); for instance, in FIGURES l and 5,additional cameras and projectors would be at someangle to the plane ofthe paper, or, alternatively, the object and the transparentdifferentially photosensitive material might be rotated. This wouldadjust for diminution of light where a surface traversed by a contourline was at an acute angle, over a portion of its length, to the linejoining any projector and the object, and would provide coverage of topandbottom as well as side surfaces, and of surfaces undercut withrespect to any particular camera or projector. Theout-of-positionprojection of lines in FIGURE 7, where the lower portion of line 6 showncoincidence, illustrates that projectedlines must'be at'an appreciableangle to the plane containing the projectors, cameras and object in anyparticular view.

In the description above, it is intimated that" the lines must beprojected, or used as 'masks with parallel beams of light, and thereforemust probably be widely enough separated in the recording to permittheir successive projection, through the recording medium, afteradjustment on recording and re-adjustment on reprojection. This 'is notso, as narrow bands, for instance, may be originally projectedsimultaneously onto the object, and the resulting contour lines recordedon one record of each view. These adjacent lines may then be hsed asguidelines for a tracing device attached to a device outside the area ofthe recording, emitting a pencil of energy, such as a laser, and two ormore peneils of energy drawn along, guided by two or more of theequivalentcontour bandsof a set recorded in two or more views. Aspointed out, one of the views may be a virtual one, consistingof theoriginally projected lines, altered in size to that of the other recording, if necessary. Phrases such as fmultiple secondary lines and morethaii'one different anglesfare intended to include the case describedwhere onlyoneyiew is' recorded as secondary lines, and the other view.isthatj'of lines similar to those originally' projected on"the"objectwhose shape is to be reproduced, The two'or more pencils of energy willbe drawn along the sheets of pr'ojection,,"so that they occupy thesamesectionpimultaneously; for instance, pencils of light 3fC, 3h Fa'n'd3eD would be projected at the sectioniepresentd by FIGURE 7,simultaneously, with the coupled tracing device at point27,

made, visible.

FIGURE 9; point 28, FIGURE 10; and point 29, FIG- URE 11. Similarly,when three tracing devices were at points 30, 31, and 32, of recordingsshown as FIGURES 9, 10 and 11, the corresponding pencils of energy wouldbe projected along paths 3fE, 3hG and 3eB at the section shown in FIGURE12.

By this coupled tracing mechanism, and original projection of bands, asimple shape like a football could be recorded in four photographs, intetrahedral arrangement, if only two rays at intersection were requiredto activate the transparent differentially-photosensitive material, asone of each pair could be the originally projected line. For morecomplex shapes, as in portraiture, a greater number of recordings mightbe required. It is clear that if the shape is very irregular, inaddition to an increase in the number of directions from which lines areprojected onto the original object, smaller angles between views arerequired, so that the reflected and reprojected rays may replicategrooves and pits on the surface.

By differentially-photosensitive solid is meant a material which isaffected by radiation above a certain threshold of intensity, or inwhich a synergistic action produces a significant effect with two ormore different types of radiation (some photosensitive glasses are fiftytimes as sensitive to nucleation by ultra-violet light as theirtemperature is raised, as, for instance, by infra-red radiation), but inwhich no significant effect results below this threshold, or in theabsence of a synergistic effect from simultaneous exposure to differentradiation. By transparent is meant a material capable of absorbingsufficient of the radiant energy producing the image to be activatedabove a certain threshold of intensity or synergism, and with atransparency to this radiant energy sufficient to ensure that at thepoint of simultaneous intersection of the rays the activating energywill be significantly greater than at any other point in the path ofother radiation in the photosensitive solid. The invention is not to beconsidered to be restricted to recording and reprojecting visible light,but is intended to apply to any radiation which may be projected as anarrow beam to produce a significant photo effect, at the points orlines of simultaneous intersection only, within the space occupied bythe transparent dif ferendaily-photosensitive material, which is, or maybe By simultaneous is meant that time within which the desiredcumulative or synergistic effect occurs; for instance, if increase ofabsorbed heat produces the effect, one radiator could operate slightlyout of'phase in time with the other, as long as the heat from one didnot leak away before the heat added by another radiator produced thedesired effect.

If radiant energy is projected through a lens it is preferable that along-focus lens be used, so that there will be negligible divergence orconvergence of the rays, and all parts of a pencil or sheet of radiatedenergy will be substantially parallel, thereby obviating effects due toundesired dispersion and refraction. In other words, no focusing of anindividual ray should ideally be necessary, but merely adjustment sothat the rays intersect at the original angle and at the same positionwith respect to other rays, as they did when originally impinging on theshape being reproduced photographically.

Two methods have been described, one in which ind-ividual lines areprojected onto the object and one set of the resulting contour linesrecorded for direct reprojection or as guides for tracers with coupledprojectors; the other in which multiple closely spaced bands wereprojected on the object and the resulting sets of multiple contour linesused to guide tracers with coupled projectors. Where automatic tracersare used, the first method is readily applicable, but complex shapescausing discontinuities in the lines might create difficulties in theuse of the second method. In this case it may be more economical toproject a group of widely-separated lines onto the object, and recordthe resulting sets of contour lines; followed by projection of anothergroup of widely-spaced lines on the object and covering areas in betweenthe first group, and subsequent recording; with continuation of theprocess to cover the entire area to be reproduced.

Instead of being coupled directly to a projector, the information from'the tracer may be fed to an intervening mechanism (such as magnetictape) for subsequent control of reproduction.

While the above description is based on the production of a permanent orsemipenmanent record in three dimensions, if a transparent material,liquid, solid or gaseous, is used which will fluoresce or :become opaquetransitorily at the line of intersection of projected rays, but notelsewhere, this method may be used to produce three-dimensional motionpictures, by the use of these multiple recordings and reprojections.

Two known devices for adjusting angles of rays entering a medium havingdifferent optical properties, where it is not convenient to shape theblock of transparent differentially-photosensitive material so thatnecessary reprojected rays enter normal to its surfaces, are shown inFIGURE 12. In the first method, monochromatic light (not necessarily inthe visible range) is shown as projected along rays 46 and 47 into amedium having a refractive index of approximately 1.5 to thiswavelength, to intersect at 52, within the space occupied by thematerial 17, after refraction at the surface to the desired angles ofintersection.

In the second method, where monochromatic light need not necessarily beused, the rays enter normally to the outer surfaces of blocks ofmaterial 48 and 49 having similar refractive indices as the transparentdifferentiallyphotosensitive material 17. If the surface of 17 has theshape of a sphere, and the inner surfaces of 48 and 49 are curved to theexact curvature of the sphere (or of a cylinder where this could beused) they will mate perfectly with the sphere, and no opticaldeviations of a ray of light passing from 48 or 49 into the sphere willtake place. In practice, some slight optical effects such as reflectionand interference might take place, which would be rendered negligible ifa liquid having the same refractive index as the material 17 was presentbetween the convex surface of the sphere, and the concave innersurfaces, 54, of blocks 48 and 49. The outer surface of blocks 48 and 49need not be tangential to the sphere, and they may be, as shown in thecase of 49, compound blocks, the outer one being, for instance,wedge-shaped to be normal to the desired angle of entrance. Then, as thesurfaces opposite the concave surfaces of blocks 48 and 49 are planesurfaces, 48 and 49 can be moved around on the surface of the sphereuntil these surface planes are normal to any rays of light which areparallel to each other as they enter blocks 48 or 49 from outside, andthey will subsequently penetrate on into the sphere with no deviationfrom their original path. The paths of rays 50 and 51 intersecting at53, are shown. As in the case of the outer portion of block 49,wedge-shaped pieces may also be used to permit normal incidence oflight, penetrating directly through a plane surface of the transparentdifferentially-photosensitive material 17, with liquid having the samerefractive index at the interfaces, if desired.

The following materials were used for test purposes, but the inventionis not restricted to these examples:

The first photosensitive material was a gel made up of approximately thefollowingconstituents: A solution containing 0.026 gram of sodiumcarbonate, 0.028 gram of potassium iodide, 0.1 gram of silver nitrateand 1.62 grams of sodium thiosulfate in 25 milliliters of water wasadded, in the dark, to a solution of 3.76 grams of gelatin in 50milliliters of warm water, to which gelatin solution had been added,before mixing with the above solution of inorganic salts, 4 millilitersof Promicrol photographic developer solution composed of the followingproportions of materials:

- Sodium carbonateanhydrous H v ,v Grams- 2 (B hydroxyethyl)aminophenolsultate?; 16 p-Hydroxyphenylamino acetic'acid"; 1.13

Sodium hexametaphos'phate' Water to make 1 liter. The. only -,quantitatively very critical irig redient in the above composition seemed tobe sodium thiosulfate in barely enough amount to prevent precipitationwhen the salts were mixed. The solutionwas allowed to set i'rfi' atransparentplastic container through which the, sheets ,of light. wereprojected to intersect within the space occupied by the gel. Fainttraces of discoloration along a sheet of projection tended'to resorbonstanding in the dark. The gel was only semi-permanent, and" lines ofintersection were viewed by red light. I j j The second material was aliquid polyester casting resin, sold commercially under the name ofBio-Plastic, and catalytically transformed to a transparent solid by aperoxide catalyst mixed in before a block was cast. This material turnedbrown at about 110.C.120 C. After slight preheating it was exposed totwo intense pencils of light intersecting within the space occupied bythe material, and lines of. intersection guided by a tracingmechanism asdescribed above, were produced within, and surrounded by, the clearplastic.

Having described the invention, what is claimed as new is: r

1. A method of three-dimensional photographic reproduction within thespace occupied by a transparent differentially-photosensitive materialwhich comprises projecting a plurality of light rays on to thethree-dimensional shape to be reproduced, eachray covering a small areaof the object, said light rays being generally distinct from each otherwhere they impinge on the object as primary lines, and being ofsufficient number that substantially the entire surface to be reproducedis outlined by the plurality of separate rays; recording images of theprimary lines projected on the object, at more than one different angle,as secondary lines; projecting simultaneously thesecondary linesproduced by viewing a primary line at more than one different angle, oneset only of secondary lines produced by recording a primary line, at anyone instant, with the sheets ofcnergy projected having thecross-sectional shape of said secondary lines passing into thetransparent ditferentially-photosensitive material, which must haveadequate space in three dimensions to contain the resultingthree-dimensional reproduction and not be merely a thin film, tointersect at the same angles as the originally projected primary linewas recorded, the additive energy from the projected secondary linesproducing an elfect which induces visibility within the space occupiedby the transparent differentially-photosensitive material that is notproduced by any one of the intersecting rays, within the time of saidsimultaneous projection; the above-mentioned secondary projections ofviews of a primary line are then extinguished, and another set ofsecondary lines, produced by viewing a primary line which was projectedon a dilferent area of the object than the preceding one, and itsimagesrecorded at more than one different angle, are projected along sheets ofenergy, said sheets of energy intersecting within the transparentdifierentially-photosensitive material at the same angles as originallyrecorded, and with a 'similarposition relative to the precedingactivated line as 'the" two primary lines were positionedon the originalobject;the process is then continued, with primary lines coveringsurfaces of the object generally distinct from each other, each -primaryline being recorded at more than one different angle,"*an"d theresulting secondary lines being projectedalong sheets of energy toproduce oneline of intersection at a time within the space occupied bythe transparent differentially} photosensitivematerial in v similarrelative shape 'a'nd" positions as the primary linesapp'eared on theoriginal object, this multiplicity of-l-ines where intersection occursthus building up a three di'mensional surfaceof photograp'hical lyaltered material within the space occupied by the transparentdifferentially-photosensitive material, which out .lines an imagesimilar in shape to that ofthe' original three-dimensional object. a

2. A method according to claim 1 in which the transparentditferentially-photosensitive material was a gel made up ofapproximately the following constit'uehtsi a solu-' tion containing0.026 gram of sodium carbonate, 0.028 gram of potassium iodide, 01 gramof 'silver nitrate, and just sufficient sodium thiosulfate to retainthese salts in solution (from 1.0 to 2.0 grams), in 25 milliliters ofwater was added, in the dark, to a solution of 3.76 grams of gelatin in50 milliliters of warm water, to which gelatin solution had been added,before mixing with the above solution of inorganic salts, 4 millilitersof Promicrol photographic developer solution composed of the.followingproportions of materials: 4

v Grams 2 (B-hydroxyethyl)aminophenolsulate 6 p-Hydr'oxyphenylaminoacetic acid 1.13 Sodium sulphite anhydrous 100 Sodium carbonateanhydrous 11.5

Sodium hexametaphosphate 1.7 Water to make 1 liter.

References Cited UNITED STATES PATENTS 2,350,796 6/1944 Morioka 156 5 82,374,981 5/1945 Cooke 156- 58 2,949,361 8/1960 A gens 96- 115 OTHER'REFERENCES Stookey, S. D.: Chemical Machinery of Photosensitive Glass,Ind. and Eng. Chem. 45, No. 1, January 1953, pp. 1 15-118. i I v NORMANG. TORCHIN, Primary Examiner. J. R. EVERETT, Assistant Examiner-. f

